Construction machines moving on a working trajectory or a working curve during operation, the approximate course of which is known prior to the start of operation, are used in different fields of construction, such as earth-moving construction or road construction. This may, for example, be the course of a road or be predetermined at least partially by obstacles such as buildings, trees, etc. In this case, the term working trajectory thus refers to a planned route the construction machine is to move along during the respective operation and along which it ideally moves during operation. For example, it is often times known for construction machines used in road construction that their working trajectory follows the planned or actual course of a road. Typical cases here are the milling track of a ground milling machine, particularly a road milling machine, a recycler, a stabilizer or a surface miner, the road surface applied by a road paver, or a lane processed by a grader. Thus, the working trajectory refers to the path which is to be processed by the respective construction machine and along which said machine moves during operation.
In many cases, operation of such a construction machine depends on at least one operating parameter comprising different setpoint values for different points of the working trajectory. Such a working parameter may be defined by the adjustment height of a working device of such a construction machine, by the working intensity or also by the working width, for example. The term operating parameter thus refers particularly to a parameter by means of which the respective working device of the construction machine is set.
In this context, it has been common that the monitoring and control of the at least one operating parameter is performed by the operator of the construction machine. Said operator does not only have to regularly check the operation with respect to the direction and work result, but usually also needs to enter the relevant control commands with respect to the working direction and the work result. Usually, this is performed by means of a console mounted on the construction machine, particularly on the operator platform of the construction machine. However, sometimes this type of control places high demands to the construction machine operator during operation as he simultaneously needs to monitor the travel movement and the operation of the working device and partly even further functions such as loading of a transport vehicle, monitoring the filling level of a bunker, etc., and ensuring a reliable operation.
One example of a construction machine which is used along a working trajectory and the operation of which depends on at least one working parameter is a ground milling machine. Ground milling machines serve for removing the surface of ground material, for example, for milling off road surfaces. To that end, ground milling machines comprise as a special working device a rotating milling drum which is equipped with milling chisels and which is immersed into the ground and guided therethrough by the ground milling machine for milling off ground material, thus producing a milling track. Such a ground milling machine has been described in DE 10 2012 021 379 A1, for example.
For example, one operating parameter essential to the working operation of a ground milling machine is the milling depth indicating how deep the milling drum mills off the ground surface in the vertical direction relative to the original surface of the ground. Depending on the respective target of the respective operation, however, situations may occur in which the milling depth varies over the working trajectory. Examples of such a variation of the milling depth may be milling a ramp between the milling bed and the non-processed ground, on which the ground milling machine may, for example, move out of the milling track, obstacles in the milling path, for example, storm drains, which are not to be milled over, etc.
Further examples of construction machines also moving over comparatively long sections along a working trajectory during operation are, in particular, road construction machines such as road pavers (as described in DE 10 2013 007 061 A1) or recyclers/stabilizers (as described in DE 10 2012 024 769 A1), or also earth-moving machines such as graders or cable laying machines (as described in EP 2246485 A1, for example).
Thus, said construction machines have in common that, in regular operation, they often times move along a path or working trajectory along which the working process is performed. It is known and common for such machines and working operations that marks are manually placed on the ground along the working trajectory prior to the actual working operation, which represent working instructions to the operator of the respective ground processing machine. For example, in this context it is known for a ground milling machine, particularly a road milling machine, that the desired milling depths are sprayed onto the ground as numbers. Then, the operator of the machine has to continuously check during operation whether marks are placed on the ground and, if so, which changes are required for the operation of the ground processing machine.